Circulators are key building blocks in next generation microwave systems for Simultaneous Transmit and Receive Radios (STAR) and Quantum Computers. State-of-the-art circulators have a ferro-magnet that breaks reciprocity but is hard to scale down to sub-mm dimensions for integrating with on-chip electronics. The need is even more pressing in photonic integrated circuits where it is essential to isolate the laser from reflections of downstream components.
Over the last few years there has been outstanding theoretical and experimental progress in ferrite-free RF and optical non-reciprocal technologies. In this talk I will convince you that in order to build superb non-reciprocal systems, all you need is a design library, a foundry technology and generous collaborators. I will demonstrate a RF circulator built using Broadcom's film bulk acoustic resonators (FBAR) and highlight the advantages of mechanical coupling that help us achieve excellent power handling and bandwidth. In the second half of the talk I will show how we leverage HBAR (the FBAR's cousin or forefather?) to modulate optical ring resonators and demonstrate optical isolation. If time permits, I will conclude my talk by providing a glimpse of how we are leveraging these technologies to achieve coherent quantum transduction between qubits, acoustic phonons and flying photons.
The presented results are from very close collaborations with Dr. Richard Ruby’s group at Broadcom, Professor Tobias Kippenberg’s group at EPFL and Professor Greg Fuchs’ group at Cornell.